linux-kernel - Re: [PATCH 1/3] perf tools: Fix period/freq terms setup

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Date:   Fri, 2 Feb 2018 13:04:34 -0800
From:   Stephane Eranian <eranian@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 1/3] perf tools: Fix period/freq terms setup

On Fri, Feb 2, 2018 at 12:40 PM, Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
> Em Fri, Feb 02, 2018 at 05:28:49PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Fri, Feb 02, 2018 at 10:45:46AM -0800, Stephane Eranian escreveu:
>> > Otherwise, I tested what you have written so far and it works.
>
>> So I take that as a Tested-by: Stephane and will apply the patches, Jiri
>> can continue working on these other aspects, right?
>
> I also added this for the casual reader to get up to speed more quickly,
> please check that it makes sense.
>
>     Committer note:
>
>     When we use -c or a period=N term in the event definition, then we don't
>     need to ask the kernel, via perf_event_attr.sample_type |=
>     PERF_SAMPLE_PERIOD, to put the event period in each sample, as we know
>     it already, it is in perf_event_attr.sample_period.
>
Not quite. It depends on how each event is setup. I can mix & match period
and frequency. The PERF_SAMPLE_PERIOD can be dropped only if all the
events use a fixed period either via period=N or -c.

I hope that perf report can deal with config mixing period and fixed
mode correctly.